Background: Lung cancer, especially non-small cell lung cancer (NSCLC), poses a significant health challenge globally due to its high mortality. Afatinib, a second-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), has shown superior efficacy over traditional chemotherapy in NSCLC treatment. However, issues like secondary resistance and adverse effects call for alternative therapies. HAD-B1, comprising 4 herbal medicines, has shown promise in lung cancer treatment in both preclinical and clinical settings. This study assesses the combination of HAD-B1 and Afatinib in advanced NSCLC patients to potentially improve outcomes by addressing the limitations of current EGFR-TKI therapies. Method: A randomized, open-label trial evaluated the efficacy and safety of HAD-B1 with Afatinib in 90 EGFR-mutation-positive NSCLC patients. Participants were divided into treatment and control groups, receiving Afatinib with or without HAD-B1. The study focused on the initial dose maintenance rate and disease control rate (DCR) of Afatinib, alongside secondary outcomes like survival rates and quality of life, under continuous safety monitoring. Results: Among the 90 participants, no significant difference was found in initial dose maintenance (60.98% in the treatment group vs 52.50% in the control, P = .4414) or DCR (80.49% vs 90.00%, P = .2283). Secondary outcomes like PFS, TTP, and OS showed no notable differences. However, physical functioning significantly improved in the treatment group ( P = .0475, PPS group). The control group experienced higher rates of adverse events of special interest and adverse drug reactions ( P = .01), suggesting HAD-B1 with Afatinib might enhance physical function without increasing adverse effects. Conclusion: Combining HAD-B1 with Afatinib potentially improves quality of life and reduces adverse events in advanced NSCLC patients. Further research is necessary to confirm the long-term benefits of this combination therapy, aiming to advance NSCLC treatment outcomes. Trial registration: Clinical Research Information Service (CRIS) of the Republic of Korea, https://cris.nih.go.kr/ (ID: KCT0005414).